1. Field of the Invention
This invention relates to a medical and surgical laser probe and more particularly to a medical and surgical laser probe with a conically tapered rod connected to the tip end of an optical fiber extending from a body of a medical and surgical laser system.
2. Description of Prior Art
Recently, there has been developed and practically used a non-contact type laser irradiation system using an optical fiber for carrying out incision of tissue of a living organism by irradiating laser beam through the optical fiber without contacting the affected part of the tissue. This type of non-contact laser irradiation system effects incision and coagulation by irradiating laser beam such as YAG laser, Ar laser, etc. from the tip end of an elongated quartz core, laser beam guide, made of a single quartz fiber connected optically to a laser source.
Such a non-contact laser irradiation system is rather poor in operating efficiency because it effects the incision without contacting the tissue and without confirming or inspecting the incision condition. This conventional laser irradiation system has another problem that reproducible irradiation effect can not always be obtained. In general, it is required to keep a distance between the tip end of the optical fiber and the tissue to be constant to provide laser beam irradiation of constant energy density. However, in the conventional non-contact laser irradiation system, it is difficult to keep the distance constant, and especially it is difficult to control a distance from the tissue when the system is applied to a laser treatment through an endoscope. In addition, the non-contact irradiation system has such a fatal disadvantage that the laser beam is backscattered from the surface of the tissue and a considerable percentage of the irradiated laser beam energy is lost. In this connection, it is to be noted that when the quartz core is kept in contact with the tissue during the irradiation of laser beam, heat is generated at the contact portion and the end of the quartz core is burnt and broken. Thus, it is not possible to use the conventional laser system in contact with the tissue.
Furthermore, since the divergency angle of laser beam irradiated from the conventional quartz core is as narrow as 7.degree. to 10.degree., the energy density is not lowered so much even at a position distanced from the irradiation point. Thus, there is caused such an undesirable effect that laser beam of high energy density is irradiated to the tissue around the portion which is being subjected to incision, too, to cause necrosis thereof.
To solve the above-mentioned problems involved in the conventional non-contact laser irradiation system, it may be proposed to provide a quartz rod formed in a tapered shape so as to allow laser beam to leak out from the tapered surface and let laser beam component from the tip end thereof irradiate onto the tissue in contact with the tissue. However, with this quartz rod, the energy density of the laser beam emitted from the tip end of the rod is rather low because of the leakage of laser beam from the tapered surface, so that incision of the tissue cannot be effected with high efficiency.